Kaczynski and his identical twin, Jaroslaw, rose to the top of Polish politics in 2005 when their Law and Justice Party swept to power. With Lech as president and his brother as prime minister, the snowy-haired siblings with boyish faces led their country to the right.
Despite Poland's membership in the European Union, Lech Kaczynski was adamant that Warsaw not become entangled in continental politics and bureaucracy. His close alliance with the United States agitated European leaders, especially during the George W. Bush administration, which was deeply unpopular in much of Europe.
The Cold War left a deep imprint on Kaczynski, who until his death at 60 remained suspicious of Moscow's ambitions in Eastern Europe and Central Asia. He supported democracy movements in Ukraine and Georgia, and believed that expanding the North Atlantic Treaty Organization to former republics of the Soviet Union and its onetime satellites was a crucial deterrent to any Russian aggression.
At home, Kaczynski, who was mayor of Warsaw before becoming president, sought to expose former communists and cleanse what he and his brother regarded as pervasive liberalism. He took a hard line against homosexuality and often assailed salacious magazines and TV shows.
His critics regarded him as a politically dangerous mix of Polish nationalism and religious conservatism. But for many Poles, remembering his courageous stand with Solidarity leader Lech Walesa and others in the movement that challenged Poland's communist regime, Kaczynski was a touchstone of the post-World War II era.
Supporters believed his policies were what a proud yet insecure Poland needed to emerge as a strong political voice between Western Europe and Warsaw's onetime master. But Kaczynski was expected to have to fight hard for reelection this year.
Born June 18, 1949, in Warsaw, the Kaczynski twins came to public attention in the 1960s as mischievous boys in the allegorical film "The Two Who Stole the Moon."
Their family history was replete with stories of Polish bravery.
Their father was a fighter with the Polish resistance during World War II; their mother nursed wounded soldiers.
In the 1970s, the brothers joined the anti-communist underground and later Walesa's Solidarity movement. Kaczynski was not a charismatic speaker, but his steely disdain for the communist era and populist sound bites won over much of the country.
"We must turn the state around to face its citizens," he said during his campaign for the presidency. "The scale of the repair will be so great that Poland will become a new republic."
His brother stepped down as prime minister in 2007 but remains chairman of the Law and Justice Party.
Kaczynski's wife, Maria, an economist, died with him in the crash.
The couple is survived by their daughter.
Times staff writer Megan K. Stack in Moscow contributed to this report.